Fig. 6

The effects of trastuzumab on HER2 phosphorylation in CHO-K6 cells by immunofluorescence. CHO-K6 cells were treated with trastuzumab at concentrations ranging from 0.1–10 μg/ml for 1 h. The phosphorylation of HER2 at Y1005 (a), Y1112 (b), Y1127 (c), Y1139 (d), Y1196 (e), and Y1248 (f) were then examined by immunofluorescence as described in Methods. The localization of trastuzumab was revealed by TRITC-conjugated donkey anti-human IgG. The localization of HER2 was revealed by rabbit anti-phosphoHER2 antibody followed by FITC-conjugated donkey anti-rabbit IgG. The cell nuclei were counter stained with DAPI. Yellow indicated the co-localization of trastuzumab and phosphoHER2. The cells treated with normal human IgG (10 μg/ml) were used as negative controls. Size bar: 10 μm